Balers are machines that can be self-propelled but are more commonly towed behind a tractor and driven from the tractor take-off shaft. They fall into two types, namely round balers and square balers. Round balers are used to produce cylindrical bales that are normally wrapped in a mesh or a film after they have been formed. Square balers produce square-sided bales that are tied by separate loops of twine spaced across the width of each bale. The present invention is only applicable to square balers.
To explain, by way of background, the construction and operation of square balers and knotters of the type to which the present invention relates, reference will be made to the accompanying FIGS. 1, 2 and 3. The three drawings are derived from and more fully explained in U.S. Pat. No. 4,142,746, which is imported herein by reference. In these drawings, which will be described herein only to the extent necessary for an understanding of the present invention:
FIG. 1 is a fragmentary, elevational view of a baler;
FIG. 2 a diagrammatic view of a complete and a partial double-knotted loop; and
FIG. 3 is an enlarged, fragmentary, elevational view of the knotter, needle and associated mechanisms in mid cycle.
The baler 20 partially illustrated in FIG. 1 has a rectangular bale case 22 that is supported by one or more ground wheels 24. The bale case 22 defines a bale chamber 26 that is loaded through a curved duct 28 approaching the case 22 from its lower end. A plunger 30 reciprocates within the bale case 22 to pack intermittently fresh charges of material from the duct 28 rearwardly in the chamber 26. When the bale reaches a predetermined size, a trigger 34 is pulled by a rod 36 connected to a suitable bale length sensor (not shown) to engage a dog clutch 38. This connects a knotter 40 and a needle 42 to a source of driving power by way of a drive chain 44 associated with the clutch 38, so as to initiate the tying operation.
The needle 42 is mounted on the bale case 22 by a pivot 46 and is swung back and forth through the bale chamber 26 by a linkage 48 which is activated by the clutch 38. The needle 42 has a rest position fully below the bale case 22 as illustrated in FIG. 1 and a position extended completely across the bale case 22. The tip of needle 42 has an eyelet 50 (see FIG. 3) defined between two transversely extending rollers 58,60 through which a strand of twine is threaded.
FIG. 2 shows the nature of the binding loop that is produced in the present invention. The finished product is in the nature of a loop 62 that completely surrounds the finished bale. The loop 62 is made from two strands of binding material, namely a first strand 64 extending along the top side of the bale and a second strand 66 along the bottom of the bale and its two opposite ends. Two knots 68 and 70 appear in the loop 62 at those locations where the strands 64 and 66 meet.
To the left of the loop 62 in FIG. 2 there is shown a partial loop 62a which is in the process of being formed. The top strand 64a is drawn from a source of supply 72, while the bottom strand 66a emanates from an entirely separate, second, source of supply 74. At the particular point in the sequence chosen for illustration, the knot 68a has been formed shortly after the knot 70 was formed, and the bale is approaching that length where the needle 42 is ready to swing into operation and present the strands 64a and 66a to the knotter 40 to form the second knot.
As better shown in FIG. 3, the knotter 40 includes a generally circular element 76 that is secured to a drive shaft 78 for rotation with the latter through one full revolution when the clutch 38 is engaged. The knotter 40 includes a forwardly inclined frame 80, which is conventionally attached to the top of the bale case 22 and additionally supports various other twine engaging components used in forming the knots in response to rotation of the element 76.
These twine engaging components include a rotary bill hook member 82 supported by the frame 80 for rotation about an inclined axis 84, a multi-disc holder 86 rearwardly adjacent the bill hook 82 for the holding strands 64a and 66a in position for engagement by the bill hook 82 during rotation of the latter, and means for releasing the connected strands from the holder 86 in the form of an arm 88 pivoted to the frame 80 by a bolt 90. The lower end of the arm 88 is forked, defining a crotch 92 that opens away from the holder 86 beneath the bill hook 82. The crotch 92 carries a cutter between the bill hook 82 and the holder 86 for severing the strands 64a, 66a in response to swinging movement of the arm 88 in the proper direction. Such movement of the arm 88 to operate the cutter also serves to engage the proximal areas of the crotch 92 with a knot formed on the bill hook 82 for stripping such knot off the bill hook 82.
In order to transmit driving power from the element 76 to the bill hook 82, the latter is provided with a gear 96 which is disposed for meshing engagement with a pair of circumferentially spaced gear stretches on the element 76. Similarly, driving power is transmitted to the discs 86 of the holder 86 through a worm gear drive 102 and a bevel gear 104 in position for sequential meshing engagement with a pair of circumferentially spaced gear sections on the element 76. Power to swing the arm 88 about the pivot bolt 90 is obtained through a cam follower 110 at the upper end of the arm 88 beyond the pivot bolt 90 which is disposed within a cam track 112 on the element 76. A pair of circumferentially spaced cam shoulders in the track are positioned to sequentially engage the follower 110 to operate the latter.
The type of knotting system shown in FIGS. 2 and 3 and described in U.S. Pat. No. 4,142,746 is known as a double knotter for reasons that are apparent from FIG. 2. In particular, two knots are present in each loop surrounding a bale and as soon as a knot 70 is formed to complete a bale a second knot 68a is formed to tie the strands of twine from the sources 72 and 74 to one another to commence the next bale. Once the second knot 70 has been tied, both strands are released from the knotter and are free to move as the bale grows. This type of knotter is to be distinguished from single knotters in which one end of a single strand of twine is clamped in the knotter as the bale grows. When the bale is complete, the other end of the strand is brought by the needle to the knotter after having the twine has been passed around the bale, and it is tied to the end previously gripped by the knotter. After having been severed from the tied bale, the end of the twine remains gripped in the knotter for the commencement of the next bale. The present invention is only applicable to double knotter, as described in U.S. Pat. No. 4,142,746 for reasons that will be made clear below.
It is sometimes desired to form a large bale by tying together several slimmer bales, which will herein be termed “slices”. If a bale has, say, six twines tied around it, one could actuate the second and fifth knotters to tie twine around every single slice and the remaining four knotters less frequently to tie knots around a completed bale made up of several slices.
A baler that operates in this manner is described in EP 1,411,759. In this patent, two separately movable groups of needles are provided, which are pivotable either about spaced parallel axes or about concentric axes. One group of needles comprises the two needles used to tie the slices and is operated after each slice has been formed and the other group of needles carries the remaining four needles and is operated only when a complete bale comprising the required number of slices has been formed.
The prior art balers capable of producing bales in which slices are separately tied thus require special needle yokes which allow groups of needles to be raised separately through the bale chamber. If two separate yokes pivotable about spaced parallel axes are used, the needles of the two groups then need to be of different length.
The present invention seeks therefore to provide an alternative and simpler construction of a knotting system which enables the formation of a bale made up of several individually tied slices while requiring no modification to the yoke or needle assembly.